1. Technical Field
The present disclosure relates to a hot melt apparatus. More particularly, the present disclosure relates to a hot melt apparatus serves to melt a plastic material so as to form a hot melt head.
2. Description of Related Art
Currently, many parts of common consumer electronics on the market (such as mobile phones, computers, digital cameras) are made from plastic materials. In order to reduce product cost and at the same time make the products thinner, nowadays the connections between plastic parts and between plastic part and metal part are mostly formed through thermal welding.
For example, when a plastic part is welded to a metal part, the thermal fixing pillar of the plastic part first passes through the hole of the metal part corresponding to the thermal fixing pillar, then a hot melt process is performed to the thermal fixing pillar by a thermal melting apparatus. Since the hot melt surface of the hot melt apparatus is generally a concave surface, under normal circumstances, the hot melt head of the molten thermal fixing pillar thus formed is in a mushroom-head shape. After being cooled and solidifies, the hot melt head will be embedded in the hole of the metal part so that the plastic part can be firmly bonded to the metal part.
However, during the hot melt process, in which the hot melt surface is faced with the thermal fixing pillar, the hot melt surface and the thermal fixing pillar are in close contact with each other and air between the hot melt surface and the thermal fixing pillar is expelled. Therefore, a vacuum adsorption effect is formed between the hot melt surface and the hot melt head when the hot melt apparatus is moved away after the hot melt process is completed. Owing to the vacuum adsorption effect, the hot melt head has not completely solidified is possibly pulled. As a result, the hot melt head curved up or even falls off (that is, the whole hot melt head is pulled away) to cause weld failure problem.
For the forgoing reasons, there is a need for solving the above-mentioned problems by providing a hot melt apparatus, which is one of the subjects that the industry eagers to invest R&D resources in.